20 lines
424 B
Text
20 lines
424 B
Text
a b : ℕ,
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a_1 : a ≠ b,
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H : a = b
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⊢ false
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-------
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a b : ℕ,
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a_1 : ¬¬a = b,
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H : ¬a = b
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⊢ false
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-------
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by_contradiction.lean:22:3: error: tactic by_contradiction failed, target is not a negation nor a decidable proposition (remark: when 'local attribute classical.prop_decidable [instance]' is used all propositions are decidable)
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state:
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p q : Prop,
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a : ¬¬p
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⊢ p
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-------
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p q : Prop,
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a : ¬¬p,
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H : ¬p
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⊢ false
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